9 times out of 10 leaking vivi novas are down to the head not being screwed into the centre post properly.
If the heads not tightly screwed into the centre post then liquid seeps inside it and leaks out of the bottom. When you get a new one out of the box the heads not screwed on tight enough (I have no idea why) so if you don't tighten the head up and use it as it comes it will leak every time.